Quantum Chemistry Calculations on the Mechanism of Isoquinoline Ring-Opening and Denitrogenation in Supercritical Water

Computational studies at the M06/6-311G­(d,p) and M06-2<i>X</i>/6-311+G­(d,p) levels were performed to explore the detailed mechanism of isoquinoline ring-opening and denitrogenation in a supercritical water system. Three reaction paths with the same product, 2-(2-oxoethyl) benzaldehyde, were supported by the computational results. The rate-limiting step in the major degradation reaction is an addition reaction at the N position. H₂O is added to both the 1C–2N double bond (1C–2N addition reaction) and the 2N–3C double bond (2N–3C addition reaction) of the isoquinoline molecule, where the oxygen of H₂O is added to the carbon atom. The energy barrier of the 1C–2N addition reaction is 52.7 kcal/mol, while that of 2N–3C addition (from Path 6) is 60.1 kcal/mol. From catalysis by two water molecules, the barrier of 1C–2N addition (Reaction (1)) is reduced to 27.5 kcal/mol. Catalysis from water molecule clusters is shown to considerably affect the process of isoquinoline ring-opening and denitrogenation, as indicated by comparing the reaction energy barrier heights with and without water catalysts

Detection of Liquid Penetration of a Micropillar Surface Using the Quartz Crystal Microbalance

A quantitative characterization of the wetting states of droplets on hydrophobic textured surfaces requires direct measurement of the liquid penetration into surface cavities, which is challenging. Here, the use of quartz crystal microbalance (QCM) technology is reported for the characterization of the liquid penetration depth on a micropillar-patterned surface. The actual liquid–air interface of the droplet was established by freezing the droplet and characterizing it using a cryogenically focused ion beam/scanning electron microscope (cryo FIB-SEM) technique. It was found that a direct correlation exists between the liquid penetration depth and the responses of the QCM. A very small frequency shift of the QCM (1.5%) was recorded when the droplet was in the Cassie state, whereas a significant frequency shift was observed when the wetting state changed to the Wenzel state (where full liquid penetration occurs). Furthermore, a transition from the Cassie to the Wenzel state can be captured by the QCM technique. An acoustic–structure-interaction based numerical model was developed to further understand the effect of penetration. The numerical model was validated by experimentally measured responses of micropillar-patterned QCMs. The results also show a nonlinear response of the QCM to the increasing liquid penetration depth. This research provides a solid foundation for utilizing QCM sensors for liquid penetration and surface wettability characterization

Quantification of Particle Filtration Using a Quartz Crystal Microbalance Embedded in a Microfluidic Channel

To quantify colloidal filtration, a quartz crystal microbalance (QCM) with a silicon dioxide surface is embedded on the inner surface of a microfluidic channel to monitor the real-time particle deposition. Potassium chloride solution with micrometer-size polystyrene particles simulating bacterial strains flows down the channel. In the presence of intrinsic Derjaguin–Landau–Verwey–Overbeek (DLVO) intersurface forces, particles are trapped by the quartz surfaces, and the increased mass shifts the QCM resonance frequency. The method provides an alternative way to measure filtration efficiency in an optically opaque channel and its dependence on the ionic concentration

Current variation obtained during the preparation of CLTO and CSTO.

<p>The total anodization time was 1 h.</p

Pd-Catalyzed Divergent C(sp²)–H Activation/Cycloimidoylation of 2‑Isocyano-2,3-diarylpropanoates

A Pd-catalyzed site-selective C­(sp²)–H activation/cycloimidoylation of 2-isocyano-2,3-diarylpropanoates to construct diverse cyclic imine products has been developed. Six-membered 3,4-dihydroisoquinolines containing a C3 quaternary carbon center were generated dominantly by using bulky Ad₂P<i>n</i>-Bu as a ligand, while five-membered 1,1-disubstituted 1<i>H</i>-isoindoles were formed preferentially in the presence of bidentate phosphine ligand DPPB. The selectivity for 1<i>H</i>-isoindole formation was enhanced by using steric hindered aryl iodides. DFT calculations suggested that the experimentally observed ligand-controlled selectivity was a result of <i>trans</i> effect

SEM images of the CLTO films formed in the electrolyte of EG +10%H₂O +0.25%H₃PO₄+3%NH₄F.

<p>(a) top view; (b) a fragment (c) the magnification of (a); (d) cross-sectional view.</p

XRD patterns of (a) the as-prepared coral-like Ta₂O₅ and (b) the calcined sample.

<p>XRD patterns of (a) the as-prepared coral-like Ta₂O₅ and (b) the calcined sample.</p

SEM image of the CSTO film formed in the electrolyte of EG +70%H₂O +0.25%H₃PO₄+3.6%NH₄F.

<p>SEM image of the CSTO film formed in the electrolyte of EG +70%H₂O +0.25%H₃PO₄+3.6%NH₄F.</p

Characterization of Diterpenes from Euphorbia prolifera and Their Antifungal Activities against Phytopathogenic Fungi

Euphorbia prolifera is a poisonous plant belonging to the Euphorbiaceae family. In this survey on plant secondary metabolites to obtain bioactive substances for the development of new antifungal agents for agriculture, the chemical constituents of the plant <i>E. prolifera</i> were investigated. This procedure led to the isolation of six new and two known diterpenes. Their structures, including absolute configurations, were elucidated on the basis of extensive NMR spectroscopic data analyses and time-dependent density functional theory ECD calculations. Biological screenings revealed that these diterpenes possessed antifungal activities against three phytopathogenic fungi. The results of the phytochemical investigation further revealed the chemical components of the poisonous plant <i>E. prolifera</i>, and biological screenings implied the extract or bioactive diterpenes from this plant may be regarded as candidate agents of antifungal agrochemicals for crop protection products

Systematic Approach to In-Depth Understanding of Photoelectrocatalytic Bacterial Inactivation Mechanisms by Tracking the Decomposed Building Blocks

A systematic approach was developed to understand, in-depth, the mechanisms involved during the inactivation of bacterial cells using photoelectrocatalytic (PEC) processes with <i>Escherichia coli</i> K-12 as the model microorganism. The bacterial cells were found to be inactivated and decomposed primarily due to attack from photogenerated H₂O₂. Extracellular reactive oxygen species (ROSs), such as H₂O₂, may penetrate into the bacterial cell and cause dramatically elevated intracellular ROSs levels, which would overwhelm the antioxidative capacity of bacterial protective enzymes such as superoxide dismutase and catalase. The activities of these two enzymes were found to decrease due to the ROSs attacks during PEC inactivation. Bacterial cell wall damage was then observed, including loss of cell membrane integrity and increased permeability, followed by the decomposition of cell envelope (demonstrated by scanning electronic microscope images). One of the bacterial building blocks, protein, was found to be oxidatively damaged due to the ROSs attacks, as well. Leakage of cytoplasm and biomolecules (bacterial building blocks such as proteins and nucleic acids) were evident during prolonged PEC inactivation process. The leaked cytoplasmic substances and cell debris could be further degraded and, ultimately, mineralized with prolonged PEC treatment